1. Field of the Invention
The invention relates in general to an inductance structure, and more particularly to a dual inductance structure.
2. Description of the Related Art
Along with the growth in the industry of wireless communication, more and more communication products are developed and provided, and how to miniaturize electronic products to improve portability has become one of the objectives to achieve. Passive elements such as resistor, capacitor, and inductance of many communication products are implemented on an integrated circuit. When passive elements being integrated are used in an electronic device, a lot of space is saved.
Referring to both FIG. 1A and FIG. 1B. FIG. 1A shows a conventional structural diagram of a miniaturized bandpass filter. FIG. 1B shows an equivalent circuit diagram of the miniaturized bandpass filter in FIG. 1A. As indicated in FIG. 1A, the miniaturized bandpass filter 100 includes a conductor 102, a conductor 104, a conductor 106, a conductor 108 and a conductor 110, wherein the conductor 102 and conductor 104 are separated by a distance W1. The miniaturized bandpass filter 100 has an input port PORT1 and an output port PORT2. Referring to both FIGS. 1A and 1B at the same time. The conductor 102 can be equivalent to an inductance L1, and the conductor 104 can be equivalent to an inductance L2. The conductor 106 can be equivalent to a capacitor C1, the conductor 108 can be equivalent to a capacitor C2, and the conductor 110 can be equivalent to a capacitor Cp. The input port PORT1 corresponds to the input port P1 of the equivalent circuit, and the output port PORT2 corresponds to the output port P2 of the equivalent circuit. The inductance L1 and the inductance L2 have the effect of mutual inductance. As we may know that the smaller the distance W1 is separated the larger the mutual inductance is induced, we may have the mutual inductance value between the inductance L1 and the inductance L2 being increased. If the inductance element used in an electronic device requires a smaller mutual inductance value and maintains the respective self inductance value of the inductance L1 and the inductance L2 at the same time, the distance W1 needs to be increased. In this way, the smaller mutual inductance value may thus be obtained, but the circuit layout area may be increased and a large space of the electronic device may also be occupied. Thus, how to effectively reduce the miniaturized bandpass filter so as to save the space of electronic device has become an important subject for further research and development.